1. Field of the Invention
This invention relates to apparatus for and methods of converting an input analogue voltage into a digital representation.
2. Prior Art
It is well-known to change an analogue voltage to a digital representation by utilising a voltage divider to divide a known reference voltage into a number of equal intervals and then to compare the unknown input analogue voltage with the output voltages from the various stages of the divider to detect when the input voltage is equal to one of the output voltages.
With such an arrangement, the analogue-to-digital conversion is carried out with a resolution which is determined by the number of stages in the voltage divider. There is thus a limit to the resolution which can be achieved.
The potential divider, from a practical point of view, also may put a limit on the accuracy with which the conversion can be achieved. Thus, if there are 200 divider stages, any 100 stages must equal (within 1 stage) any other 100 stages to give 1% accuracy. It is thus difficult and expensive to implement an accurate analogue-to-digital conversion of more than, say, 256 divisions.